Project doesn't run with docker-compose

I'm trying to run your project on a linux machine (ubuntu 20.04) with docker compose. Usually I should be able to run it just with docker-compose up -d, however it's not the case. Neither the frontend nor the backend are working. With the following modification the frontend seems to be working:

-    "docker-start": "NUXT_HOST=0.0.0.0 yarn --verbose install --prefer-offline --frozen-lockfile && yarn --verbose serve",
+    "docker-start": "NUXT_HOST=0.0.0.0 yarn install --prefer-offline --frozen-lockfile && yarn --verbose serve",

However, I cannot get to work the backend. The error displayed is:

backend_1   | 2021/11/04 12:05:44.064 [E] [Container.go:62]  Could not start Que: ERROR: relation "que_jobs" does not exist (SQLSTATE 42P01)
backend_1   | 2021/11/04 12:05:44.066 [E] [db.go:49]  Error connecting to Postgres pg: SSL is not enabled on the server
backend_1   | 2021/11/04 12:05:49.067 [E] [db.go:49]  Error connecting to Postgres pg: SSL is not enabled on the server
backend_1   | 2021/11/04 12:05:54.069 [E] [db.go:49]  Error connecting to Postgres pg: SSL is not enabled on the server
backend_1   | 2021/11/04 12:05:59.071 [E] [db.go:49]  Error connecting to Postgres pg: SSL is not enabled on the server
..... (the last line repeats over and over again every 5 seconds it seems) .....

In the docker-compose.yml file I tried to change the following:

-      DATABASE_URL: postgres://postgres:postgres@db/postgres
+      DATABASE_URL: postgres://postgres:postgres@db/postgres?sslmode=disable

However it doesn't seem to be working either. Any ideas?