Hi,
Can I ask you where in the interface you are trying to embed this tag? If this is a page load rule, the third-party sequential HTML section should allow this. You could also try placing this inside one of the tools in the same section.
Typically, JavaScript would go in one of the JavaScript sections. However, if the <script> tag is needed, you'll need to place it in the sequential HTML section as referenced in the following documentation.
https://marketing.adobe.com/resources/help/en_US/dtm/load_order.html
"Sequential HTML: Injected into <HEAD/> below DTM library include script if <SCRIPT/> tags are used, otherwise is injected at top of <BODY/>"
Cheers,
Jantzen