This happens for the following reasons:
When the "Visible to" field is left empty in the Guide card which is why the sentence "[...] you will make your guide publicly available to these workspaces" seems incomplete.
There's 0 steps in your instructions
The instructions are hidden for the users (eye icon)
Based on your platform role, see what you can do:
You're an Editor
1. Make sure to have steps in your instructions.
2. Make sure the instructions are made visible (the eye icon is not showing)
3. Ask an Admin to fill in "Visible to" and click Save. Once this action is performed, you will be able to Publish Guide.
You're an Admin or a Platform Admin
1. Head to the Guide card
2. Click the Edit button
3. Click Visible to field
4. Select the workspace the guide should be available for
5. Click Save Draft
6. Optional: Click Publish Guide and inform your Editor that the Guide has been published.