Citrix Gateway Connector for Exchange ActiveSync is not made to act on HTTP GET requests by default

Citrix Gateway connector for Exchange ActiveSync

https://docs.citrix.com/en-us/xenmobile/server/gateway-connector-exchange-activesync.html

Manual Configuration of Citrix Gateway connector for Exchange ActiveSync on the NetScaler

https://support.citrix.com/article/CTX200220

Exchange ActiveSync: HTTP Protocol (Messages Transport)

https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-ashttp/09c49569-d6d3-46bf-8468-4a60b4f784e7