Simply create powerful Upload Form Builder - Formly. Let your customers upload any files to their request. You can use the drag and drop builder to determine what information you get from your requesters.
How can i change the upload field position on the product page?
The position can be changed easily if your theme is already on the newest Onlinestore 2.0 version.
Please see this tutorial -> See video
How can i allow just specific file types?
With Formly you can specify which file types can be uploaded. See this tutorial how to do it.
-> See video
How can i restrict the number of files which can be uploaded?
You can restrict the number of files which can be uploaded with Formly easily.
See this tutorial -> See video