Cannot install Plugin MRBS

When I try to install MRBS in my fresh Moodle 3.7.1, I get an error message telling me that there is an error in coding.
"Capability 'block/mrbs:viewmrbs' was not found! This has to be fixed in code."
The mrbs is at this point partially installed, I can find it in blocks and create a block for it. But then it disappears and not all of the global roles have been created (only MRBS Viewer and Editor) and I cannot use it.

It also names a few lines where errors have occured.

What should I be doing differently? And thank you for your help and the plugin. It has become essential for our school!