You will want to go to the top left of the mods tab and find install from a file, this is where you will find the mod that you saved. Once you have navigated through all your files to find where you have saved your mod, then double click it or open it and it will be saved onto Vortex.

Where are vortex files?

After installing Vortex on your new device make sure to copy the Vortex folder found in User/AppData/Roaming/ to the same exact location on your new computer/laptop.

Can you delete vortex Downloads folder?

Delete or Move downloaded archives

Navigate to the Settings > Download tab and beneath the "Download Path" header there is a clickable link that will open your download path folder. From here you can delete the files or move them to a new location.