Set a download date you will actually keep
Put the album’s upload deadline and deletion date in your calendar as separate entries. Make an early download if you want one, then download again after the upload window closes to catch late contributions.
Keep professional deliveries separate from guest uploads. Follow your photographer’s instructions and preserve the files they supply.
Open the download before copying it
Save the ZIP somewhere you can find again, extract it and inspect the resulting folder. Open a few photos and play videos from different parts of the day. Check a file from a guest whose upload mattered to you, such as the speech clip.
If something will not open or expected files are missing, return to the source while it is still available. Keep the existing download while you investigate so a second attempt does not overwrite your only copy.
Create a copy that survives losing the first device
The Library of Congress recommends additional copies in another location as part of its personal-archiving advice. That guidance was published in 2013; it is preservation advice, not a current survey of wedding services.
For your own plan, you might keep the extracted collection on a computer, a backup drive and a separately managed remote backup. Choose storage you know how to check. Two folders on the same laptop still leave you dependent on that laptop.
Test a small restoration
Copy a photo and a video back from the backup location into a temporary folder. Open them there and compare them with the first download. Check that the other person responsible for the archive knows where it is and how to access it.
Keep a short note with the event, download date and folder names. Preserve the downloaded collection separately from cropped edits or a favourites folder, then review access when you change devices.
Sources
Practical questions
Is downloading the ZIP enough?+
Open it, check the contents and make a separate copy. An unreadable or incomplete download should be discovered while the source collection is still available.
Does a backup improve the quality of an uploaded photo?+
A backup preserves the file you copied. JoinAlbum optimises uploaded photos to at most 2,560 pixels on the long edge; ask the person who took the photo for their source file if you need it.