The wireless package that you install has to match the RouterOS version you are installing it to. You said you are running 6.22, but that you downloaded a wireless-cm2 package for "6.22rc". I can only assume you mean 6.22rc7. The "RC" means "release candidate"...in other words, a beta version. You downloaded the wireless-cm2 package that works with RouterOS 6.22rc7, not 6.22 (final release). Unless your router is also running 6.22rc7, that package will not install because of the version mismatch.
If you are indeed running 6.22 final release on your CRS125, you need to download wireless-cm2-6.22-mipsbe.npk. There is a link for this file on the MikroTik download page. Click on "mipsbe" for platform, and under there you will see a link for "Wireless CAPsMANv2". That's the one you want, not the one under the "RouterOS v6.22 release candidate special release" section (unless you really are running 6.22rc7, in which case I would suggest upgrading to the final 6.22).
Alternatively, if you download the "all packages" version of 6.22 for MIPSBE, there is a "wireless-fp-6.22-mipsbe.npk" file in there that you can install in order to use CAPsMAN version 1. wireless-cm2 is if you want to test out CAPsMAN version 2, which itself is still in beta (regardless of which version of RouterOS you are running). If you installed the "upgrade package" version of RouterOS (routeros-mipsbe-6.22.npk), then the "wireless-fp" package is already on your system and you just need to enable it by going to System -> Packages, selecting "wireless-fp", clicking "Enable", and then rebooting your router.
EDIT: I missed your last question about what to do with the BaseBox. For any access points that you want controlled by CAPsMAN, they have to have the same version of CAPsMAN (version 1 or version 2) installed on them that you have installed on your controller (the CRS125 in your case). The RouterOS version does not have to match, but the CAPsMAN package does. So, for example, you could have the CRS125 running RouterOS 6.22 and the BaseBox running RouterOS 6.21, and that is fine, but if you are using the wireless-fp package on the CRS125, you have to also use wireless-fp on the BaseBox, and if you use wireless-cm2 on the CRS125, you have to use wireless-cm2 on the BaseBox.