It is impossible to finish ShortPoint SPFx installation because while installing from Dashboard, the installation is stuck on "Provision Page References to Host Web":
The user is trying to install ShortPoint on a subsite having no access to the parent site.
The admin has to grant the user at least the Read permissions to the parent site (make him a part of the Site Visitors group). For example, if the user is installing ShortPoint SPFx on tenant.sharepoint.com/subsite, he has to at least have Read permissions to tenant.sharepoint.com.
To do this, please ask your Site Collection administrator to:
1) Open the parent site;
2) Open the parent site Site Settings (through pressing the top-right cog wheel in the Suite Bar and choosing Site Settings, or, in newer experience, Site Information > View All Site Settings);
3) Click Site Permissions:
4) Choose the Visitors group:
5) Click the arrow next to New and click Add users - Add users to this group.
6) Add the user installing ShortPoint SPFx on a subsite into the group and press Share:
Now, after the user tries to install ShortPoint SPFx onto the subsite of this site, he will have his installation finished succesfully: