Thank you Juan! Had a really nice time in Lisboa.
Juan is very helpful and even asked me if I need to wash my clothes or need a taxi to the airport.
The check-in and check out was also no problem.
The flat has everything what you need and is good located so you can walk in max. 20 minutes to most attractions.
One point to mention is that if you're above 1.80m you have to duck upstairs in the bedroom since it's quite low, but for me it was no problem :p.