DSP provides 3rd party tag which join user into interest group via Protected Audience API
3rd party script provided by ssp should embed as below
<script src="https://privacy-sandbox-demos-dsp.dev:443/dsp-tag.js" class="dsp_tag" data-advertiser="privacy-sandbox-demos-shop.dev" data-id="1f45e" data-script="afterInteractive"> </script>