I just completed a brand new fresh install of the latest version of Moodle (3.1.0) on CentOS 7.9. The first thing I wanted to do after logging in was change the theme. When I try to install the Adaptable theme, I get a dependency error that states:
"Not in the Plugins directory: theme_bootstrapbase."
However, there doesn't seem to be an option to install that theme. As a matter of fact, I can't even find it on the plugins site. Additionally, Adaptable claims it is a child theme of "Boost." I also cannot find just plain "Boost" as a theme or plugin.