Hi @moritz,
As @peter stated, odrive will use placeholders by default, so as not to waste bandwidth and local disk space. Unless you need those hundreds of gigabytes cached locally, we recommend utilizing the default placeholder ability of odrive to target only the specific data you need to access at any given time.
If you do require the data to be local and “active” once you move over to odrive, you can take a look at this post for some information on migrating existing local data like this: Any way to map existing laptop folders already synced to my services?