[Plugin: Learninglog] "The active theme is broken. Reverting to the default theme."

Hello. I am trying to install Learninglog on a local WordPress installation. Both WordPress and Learninglog were downloaded today, so they’re both up to date.

I have successfully enabled multisite support, and installed BuddyPress, as described in the instructions.

When I try to activate one of the learninglog themes, I get the error message in the topic title: “The active theme is broken. Reverting to the default theme.”

Here is what happens when I select “preview” in the “theme” section (happens to both):

https://img534.imageshack.us/f/tworkv.png/

(Also, I’m not able to register new learners in order to create an assignment. I’m just redirected from https://localhost/multisite/wp-admin/wp-admin/admin.php?page=import-user to https://localhost/multisite/wp-admin/?c=1 without anything happening)

Thanks in advance for your time
– Kristian

https://www.ads-software.com/extend/plugins/learninglog/