XDCR replication errors

I am trying to test XDCR to see how fast can replicate across different DCs but I could not make it work. I get the following errors.

Not sure if it is important one of the cluster is Couchbase 5.5 the other one is 6.0. When I added the remote cluster on the current cluster I haen’t enabled any encryption.

If I try to add encryption adding the root certificate from the other cluster this dialog close but when I try to add a replication I get an error message “Error verifying SCRAM-SHA authentication support. err=Error sending final request.: MCResponse status=AUTH_ERROR, opcode=SASL_STEP, opaque=0, msg: {“error”:{“ref”:“5ab665be-5355-4e7c-8b03-0a21d8f2fe7c”}}”

`2019-07-23 17:32:09 :MCResponse status=AUTH_ERROR, opcode=SASL_AUTH, opaque=0, msg: {“error”:{“ref”:“03cdc50f-d6bd-4623-5dab-ac19221594ce”}}

2019-07-23 17:31:09 :MCResponse status=AUTH_ERROR, opcode=SASL_AUTH, opaque=0, msg: {“error”:{“ref”:“7fd3b839-fac1-4981-299a-0b8aed21d565”}}

2019-07-23 17:30:12 :TopoChangeDet:unexpected status code, 401, in _pre_replicate response. respMap=map
2019-07-23 17:30:09 :MCResponse status=AUTH_ERROR, opcode=SASL_AUTH, opaque=0, msg: {“error”:{“ref”:“89b00a0b-c375-49bd-6e65-a809a2aaf3c4”}}

2019-07-23 17:29:12 :TopoChangeDet:unexpected status code, 401, in _pre_replicate response. respMap=map
2019-07-23 17:29:08 :MCResponse status=AUTH_ERROR, opcode=SASL_AUTH, opaque=0, msg: {“error”:{“ref”:“96d8408b-7b5e-453d-6ea8-c7a5e18e9bb3”}}

2019-07-23 17:28:08 :MCResponse status=AUTH_ERROR, opcode=SASL_AUTH, opaque=0, msg: {“error”:{“ref”:“4964624d-21ec-4415-55f7-05d54772aa18”}}

2019-07-23 17:27:08 :MCResponse status=AUTH_ERROR, opcode=SASL_AUTH, opaque=0, msg: {“error”:{“ref”:“d8e18894-3856-49b6-fcae-166d70e7e70d”}}`

How can I figure out what is the problem?

Thank you,