Currently, the "Archive" permission is not granted to the app user by default. In order to utilize the /wiki/rest/api/content/archive functionality, the app user requires the "Archive" permission. However, this permission is not automatically assigned, leading to a situation where space administrators have to explicitly grant it for each space. This manual process becomes cumbersome and non-scalable. It is worth noting that while everyone receives the "Delete" permission by default.
Additionally, having space admin privilege is not enough to archive pages and requires explicit "Archive" permission.

Suggestion:

While installing the app grant "Archive" permission of the app user by default.