Timetables are available online, whether on planner apps such as DB Navigator, SBB Mobile, etc.

There is no overnight train (anymore) in Portugal and Spain. In general they're quite rare around Europe -> not profitable, competition with low-cost flights, high-speed trains,…

In addition Portugal is badly connected to the rest of Europe. There is a daily Lisbon - Granada itinerary and that's it!

- IC Lisbon (Oriente) - Entroncamento 08:09 - 08:57

- R Entrocamento - Badajoz 09:09 - 12:54 (incl. 1h time difference!)

- R Badajoz - Merida 14:20 - 15:06

- MD Merida - Sevilla Santa Justa 15:19 - 18:58

- ARC Sevilla Santa Justa - Granada 19:20 - 21:52

What's the travel date? Please double check the times above as they could differ.

Alternatively you could catch a direct Flixbus to Sevilla, make a break there and continue in the evening:

- Flixbus (Eurail not valid) Lisbon - Sevilla 06:25 - 14:05

- break

- ARC Sevilla Santa Justa - Granada 19:20 - 21:53

Unfortunately, all night trains in Spain in Portugal are discontinued since the start of the covid pandemic. No options overnight. Crossing the Portuguese - Spanish border by train is difficult now. Best look at this page for information: https://www.seat61.com/international-trains/trains-from-Lisbon.htm

Almost all trains in Spain require reservations, only exception is for the Cercanias or Rodalias commuter trains around big cities. You can get them at the ticket office in Spain or online here at Interrail/Eurail or at a website like www.raileurope.com

Best check prices of ordinary tickets too. If Lisbon - Granada is your only option by public transport, I doubt an interrail pass will be good value.