4giving has the ability for you to receive donations directly through your website. We outline that process on the Accept donations on your website article.
WIX, however, has a handful of limitations on how they allow third party websites to operate. At this time, the only way to work with donations from 4giving on a WIX site is by linking out to your secure hosted donation page.
Go to your campaigns page and find the campaign you wish to link too.
Click on the Options button on the right side of the campaign which will take you to the individual campaign.
The options button will open a menu that has a "Copy" button. This button has the link to your fundraiser. Click on the Copy button.
You will see a notification that this has been copied to your clipboard.
Use this link as the Web Address for a button, link or image target inside of WIX.