In the Bedrock version, the Warden was not summoned even after setting up the Skulkshrieker and stepping on the Skulkshrieker repeatedly. I also tried the preview version (bedrock) and it did not work.
Linked issues
Comments 3
Sculk shriekers placed by the player are not meant to summon the warden, see MCPE-153942. You need to either find a naturally generated one or use this command:
/setblock ~ ~ ~ sculk_shrieker ["can_summon" = true]
Was the sculk shrieker naturally generated, or did you place it yourself?