Well me i try it and i put direct link and i dont have any problem .I think maybe just they dont allow it at some niches
Ok maybe it is based on niches. But have you posted affiliate links or it is your own product and you posted your site's URL?
I would recommend to grab a domain name at Godaddy and build a basic web page to capture emails, this will allow you to "own" the visitor and increase your convertion rates. I am a fan of Microsoft Bing Ads and same with Google Adwords but building my email lis is one thing I regret not doing from the start. Direct linking works but you'll bleed money if you do not retain your customers.
The proper way to direct link affiliate products on Microsoft (Bing) Ads hasn't changed much in 2021 as it was in 2017. Other than that, you have to click on your affiliate link, and add the URL you see in the actual browser in the “Final URL” field.
I would assume this is based on niches and website content. Personally, I've never had a problem getting my direct links approved.