After TotalSegmentator is installed via MITK, the install button is disabled.
Steps:

1. Press "Clear Install" -> Install button is enabled. (as expected)
2. Check the "Use Custom Env" checkbox -> Install button is disabled. (as expected)
3. Now, uncheck the "Use Custom Env" checkbox -> Install button is still disabled. (BUG!)

Unchecking Use Custom Env" checkbox should enable the install button.
Workaround: click "Clear Install" again and then the install button is enabled.