you need to step a little bit back from the door that you can read the tooltip on your mouse. Then one left click and you are in.

But also you can cange this in your options:

Gameplay - Enter buildings by touch

need to be marked on that you not have to click

If it is not working, try to do it again and right after please load up the output_log.txt which you can find in your steam folder

steam/steam_apps/common/realms of arkania/schick_hd

so if you think its a bug, i asked you to upload the output_log.txt, but you have to upload, directly after you tried to get into an temple

can you please upload me the whole File?
do you play on Linux or Win