First of all you'll need to clone this repo and build it using yarn build.
Next you'll have to clone the FastStore repo at the poc/plugins branch.
Run yarn install on the monorepo root and cd into packages/cli. In the packages/cli, run yarn build and yarn link.
For the next step, clone the starter and switch to the same poc/plugins.
Change the path of the @faststore/plugin-test on the store's package.json to where you cloned this repo, run yarn install, then run yarn link @faststore/cli.
Finally run yarn dev on the store's directory and you should see the plugin page on http://localhost:3000/my-account.
If you make any changes to either faststore/cli or the plugin you'll have to rebuild them via yarn build.