Please check what platform you have before installing:
https://github.com/SynoCommunity/spksrc/wiki/Synology-and-SynoCommunity-Package-Architectures

Install

1. In the Synology DSM web admin UI, open the Package Center.
2. Press the Manual install button and provide the SPK file.
3. Follow the wizard until done.
4. At this point tailscaled should be up and running.
5. SSH into the machine, and run sudo tailscale up so you can authenticate.