To add non-WordPress repository themes and plugins to your bundles, you can add your own custom links. Dropbox is a quick and easy way to do this, but it also will work with any link that’s set to automatically download the zip file.
Step 1: Upload your plugin or theme to Dropbox and click the share button. This will open up a modal like in the image below.
Click create link, and then copy the link.
Step 2: Head on over to you GridPane bundle and paste the link in either the theme or plugin section. To make sure the link it set to automatically download, it has to end with dl=1, NOT dl=0
E.g. dropbox.com/s/vcjfgsd8fsdjsz/awesome-plugin.zip?dl=1
Click save and you’ve now added your plugin to your bundle.