OK, I got further into the RPI4 issue.
The steps I took:
Fresh installation of Ubuntu 64bit on RPI4B Install Docker Changed the ClearML yml file to the new Mongo + Elastic versions, to support arm644. ubuntu@clearmlserver:~$ docker container list
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
995fc4aa9dcb allegroai/clearml-agent-services:latest "/usr/agent/entrypoi…" 2 hours ago Restarting (1) 16 seconds ago clearml-agent-services
587bfabfff9d allegroai/clearml:latest "/opt/trains/wrapper…" 2 hours ago Restarting (1) 52 seconds ago clearml-webserver
8c891b6a92a9 allegroai/clearml:latest "/opt/trains/wrapper…" 2 hours ago Restarting (1) 56 seconds ago clearml-apiserver
097af9489ba5 redis:5.0 "docker-entrypoint.s…" 2 hours ago Up 2 hours 6379/tcp clearml-redis
26c1667b6055 allegroai/clearml:latest "/opt/trains/wrapper…" 2 hours ago Restarting (1) About a minute ago clearml-fileserver
74966692fad7 http://docker.elastic.co/elasticsearch/elasticsearch:7.8.0-arm64 "/tini -- /usr/local…" 2 hours ago Up 2 hours 9200/tcp, 9300/tcp clearml-elastic
674ddfb82e6f mongo:latest "docker-entrypoint.s…" 2 hours ago Up 2 hours 27017/tcp clearml-mongo
CONTAINER ID   IMAGE                                                       COMMAND                  CREATED       STATUS                              PORTS                NAMES
995fc4aa9dcb   allegroai/clearml-agent-services:latest                     "/usr/agent/entrypoi…"   2 hours ago   Restarting (1) 16 seconds ago                            clearml-agent-services
587bfabfff9d   allegroai/clearml:latest                                    "/opt/trains/wrapper…"   2 hours ago   Restarting (1) 52 seconds ago                            clearml-webserver
8c891b6a92a9   allegroai/clearml:latest                                    "/opt/trains/wrapper…"   2 hours ago   Restarting (1) 56 seconds ago                            clearml-apiserver
097af9489ba5   redis:5.0                                                   "docker-entrypoint.s…"   2 hours ago   Up 2 hours                          6379/tcp             clearml-redis
26c1667b6055   allegroai/clearml:latest                                    "/opt/trains/wrapper…"   2 hours ago   Restarting (1) About a minute ago                        clearml-fileserver
74966692fad7    http://docker.elastic.co/elasticsearch/elasticsearch:7.8.0-arm64    "/tini -- /usr/local…"   2 hours ago   Up 2 hours                          9200/tcp, 9300/tcp   clearml-elastic
674ddfb82e6f   mongo:latest                                                "docker-entrypoint.s…"   2 hours ago   Up 2 hours                          27017/tcp            clearml-mongo

I don't know how to make it readable in Slack.. Sorry.
5. I got the logs for the ClearML containers:
standard_init_linux.go:219: exec user process caused: exec format error
for all the ClearML containers
6. I looked in stackoverflow - it seems like an encoding issue on your part. I just don't really understand where these files are stored and created.