The registration app has been moved and this repository is now deprecated. You can find the code at the new location:
https://github.com/catenax-ng/tx-portal-frontend-registration
If you want to check out previous versions of the code just open the according release version. The last one (also available in main) would be:
https://github.com/catenax-ng/product-portal-frontend-registration/tree/0.5.5.1