You are able to establish a training module and make it accessible for someone who may not have, and may not be required to create an account within Rosterfy.
First, you will be required to create a Training Volunteer Registration form. This form allows you to collect information such as name, email and company name / organisation.
An example is shown below: 
Once done, you're set to create online user Training and ensure it is accessible to those without a Rosterfy account.
On the 'Advanced Options' tab, you must ensure that you toggle on the 'Allow anonymous submissions' prompt, and attach your newly created Training Registration form.
Once saved, a unique URL to the External Training module will be created which you can share out and direct external users to for completion.
Note - ensure the training module is published prior to sharing the link.
If you wish, you can create a unique Email Template to be sent out to any external users upon their completion of the training module.