User can follow either of the below ways to upload the larger files:

1. Split the files within the size limit and then upload them on ADDA.
Ex- Let's say you have a file of 100 pages of total size 20MB. And the size limit you can upload is 8MB. So split the file into 3 parts, let's say the first file with 30 pages and size 7MB, the second file with 30 pages and size 7MB and third file with 40 pages and size 6MB. This way each file will be within size limit and hence can be uploaded on ADDA.
To know how to upload the file on ADDA follow the link: https://support.adda.io/portal/kb/articles/how-to-upload-admin-files

OR

2. Store file on any of the available online drive like Dropbox, and then share the link through ADDA.
To know how to upload link on ADDA follow the link: http://faq.adda.io/how-do-we-share-a-link-with-admins-all-members-only-owners/