If you are not already using Confluence, these are the options:
The cloud proposition is a very cost effective way to start, for as little as $10 per month for up to 10 users. You can always move the content to your own server instance later.
Confluence cloud is hosted with Amazon Web Services, but unfortunately it is not possible to select the geographic location of your data. Atlassian does however comply to GDPR regulations.
Well hidden on their website, Atlassian also offers a free version of the cloud proposition. While it has the same features, it lacks the possibility to define permissions on space level. This means that users have either no, or admin access to the spaces. There is no read-only option.
If you will use Confluence only for Instant 27001, this might be acceptable. And it is always possible to upgrade to the paid version later.
If you really don’t want to rely on cloud services, or want to have absolute control over your data, you can also opt for the server version. This will be a one time fee of $10 for up to 10 users.