You should see a carriage number, too.

273 is the seating car number (272 is couchette, 271 sleeper).

Unfortunately, a seating car compartment is not private.

If there's no option to choose, normally this means: seat. 

Looks like either seats or a couchette. Although on a couchette reservation I'd expect Unten / Mitte / Oben, so it's probably seats.

If I check this train for 4 people, then only seats are offered, so it could well be that there was only availability left in seating accommodation

oh no its 273!, the whole point of the trip was so the kids could go on a sleeper train! Gutted, this will be awful, especially if sharing….is there anyway to get a couchette? can you get  cancellations? this is our only night to travel due to other bookings, i didnt think it would book up so quick (its for mid august). I should have booked earlier :-(

Here you can see all the couches how will probably the train look like:

https://www.vagonweb.cz/razeni/vlak.php?zeme=DB&kategorie=EN&cislo=40237/@&nazev=&rok=2023

Under each couch there’s a gallery and seating:
 

So you can try to check there. The number 270 on the image stays for the couch number.

Couchette has just single places left, no compartment for four. 

If it's for the night train trip and if you do have railpasses and time, two possible solutions:

Leave München Hbf at 21.43 for Innsbruck (two changes at Rosenheim and Kufstein; arrives Innsbruck 23.48) and take the night train from Innsbruck. Leaves very late at 0.56. Possible, but long wait and late departure for the night train. 

Better timing but earlier from München (recommended):

Leave München Hbf at 18.52 for Bregenz (EC train), change there for Feldkirch (arrives 22.00). At 22.45 there's a night train that arrives at 22.20. It's not direct, but a nice journey to Feldkirch without long waiting times at stations. 

The night train from Feldkirch / Innsbruck to Ljubljana has still availability in a couchette (private for four people; just be patient not to select couchette with six places). 

It's the same arrival time in Ljubljana (8.09).

Hektor, thank you so much for taking the time to look up the options, its very kind.

We do not have rail passes, we are from Ireland and have never travelled in Europe by train before, so its all very new!.  (we dont have any sleeper trains in Ireland...)

I looked at the overnight Feldkirch to Ljubljana you mentioned, but there is only an option for a 6 berth couchette.  (it wont let me un-select it).  Same for the Innsbruck- Ljubljana. I dont think I would be able to change my ticket anyway, and its an extra 133 euro for the shared couchette, it would end up being too expensive for us,

thanks again for the help

One more query - we were thinking we could book the other 2 seats in the seating compartment for 6 (if they are not already booked).  but when i go on the website i dont see an option to select the seats?  

would it be possible to do this, if i phoned directly?

I just had a look and unfortunately it's not possible. 2 couchettes are already taken and 4 are remaining. All other compartments are full.

Alternative : night train from Zurich or Feldkirch to Vienna (4 people compartments available). From Vienna Eurocity to Ljubljana (07:58 - 14:00). Not ideal though...

Do you mean it is not possible to book the other 2 seats in the compartment?

Yes the 2 other berths (not seats) are already taken by other people. If you try booking for 5 or 6 people it doesn't work.

It's not possible to select specific seats, but it's possible to ask for two seats at the corridor (that's where the two missing places are) and have a look at the seats the system will give before buying them. Just click on Click here for service and price details and it's shown. 

The main problem is: Any seat that isn't taken by a real person 15 minutes after departure can be taken by anyyone else - you don't have the right to get the seats just because you did pay a reservation fee. 

2nd problem: The system wouldn't offer your missing places even when requesting seats at the corridor so there's a chance someone else did already reserve them (if you didn't buy them yourself).