Kindly welcome to the Shopify Community.
I properly read your problem and need to carefully analyze your website to provide a solution here.
Would you kindly share your website URL and if your website is password protected then also provide a password?
I will carefully check out the issue and provide a solution to you here.
Please let me know if you have any further questions.
Welcome to the Shopify community and thanks for reaching out with your questions. You can absolutely create product collections for your store and also fulfill orders automatically for digital products. What kind of digital items are you selling? The options for automatically fulfilling the orders could change depending on the size of the digital products you offer. I'll make sure to include a few options for you to choose from.
On Shopify collections refer to groupings of like items that make it easier for your customer to shop on your store. You can choose how many collections you wish to have and how your customers browse your products using this option.
You can create collections that use automatic tags to pull items in or create collections manually, where you pick and choose the items that are part of the set. You can learn more about the different collection types and how to set those up in our Help Center: Collections.
Shopify Learn: Getting Started is an awesome resource for new merchants and section 1 is how to create products and collections, it includes step by step guides and video content to help you learn as you build your store. I highly recommend reviewing the sections you need help with using this course.
If you want to use automatic collections that pull new items in as they are created, I recommend doing so using a specific product tag that is only used to puil items into your preferred collection. We see merchant using some of the other options, like keywords in a product title, but I frequently see conflicts when using those options unless you are following a very specific structure for your product creation.
These three apps are some of the most popular apps at this time for uploading and selling digital products. The Shopify digital downloads app is free to use and supported by our own in house support and technical team while the other two are made by independent developers that are part of our app store ecosystem. All three are great options and I recommend reviewing any limitations that might have (Ex: file size upload limit) to make sure they are the right fit for you.
Don't hesitate to reach out here if you have any other questions about this you need help with.