The module supports Instant Download of products when PayPal successfully confirms payment. Products can have multiple downloads uploaded for each product and Instant Download will provide multiple links for those downloads.
You can set # Extra Downloads Allowed per Order to allow for mistakes by customers. e.g. if there are 3 download components, and they downloaded one component twice, the system prevents a 4th download. If that happens, they are provided an email link to contact you and you can check their order to see how many times download has been used.
Group access can be provided for each product - for payments via PayPal with IPN, the customer will be automatically assigned to that group. Otherwise, you will need to allocate group membership manually once you are satisfied you have been paid.