Hello to our users in Europe :)
At the moment, PC Manager has not been officially rolled out in Europe. Although there is no detailed timetable to share, I'd like to tell you that the team is planning to expand the available markets to a wider range in the not too distant future.
At this stage, changing your region option in Windows Settings to the other regions outside the EU, such as the US, will allow you to download it, although I do not really recommend you try it - please remember to switch back to your current region after installing PC Manager.
There are also some 3rd parties that provide self-hosted MSIXBUNDLE packages. Before installing these packages, please check the digital signature; if the status of "Microsoft Corporation" is not OK, please DO NOT proceed.
Hope this helps :)