Recurly's own integrations marketplace leans toward accounting, tax, and fraud tools rather than CRM or marketing automation. If you're running Keap (formerly Infusionsoft) or ActiveCampaign specifically to nurture leads and follow up with customers, there's no deep native connector doing the subscriber-sync work for you out of the box, which is exactly why this is one of the more commonly searched Recurly integration pairs.
Salesforce and HubSpot sit a bit closer: both have a broad partner ecosystem, and a basic contact-sync tool can usually move a name and email across without much setup. What that basic sync almost never does is carry subscription state, plan tier, renewal date, payment health, into a field your sales or support team can actually see and act on inside the CRM they already live in.
Shopify and WooCommerce are a different relationship entirely: Recurly runs subscription billing, the storefront runs the catalog and checkout experience, and the two need to agree on who's actually paid and for what. Whether that's a clean split depends heavily on how the storefront is set up, since neither platform assumes the other exists by default.