If you look at the error message towards the bottom of the error, you'll see that the problem is that the database was starting up and therefore LabKey couldn't establish a connection to the datasource.
You need to make sure that your database is running prior to starting up Tomcat. If your database was just started up, you should give it a few minutes (at least 10) to fully come up before establishing any kind of connection to it, which includes any web applications like LabKey.
Typically, whenever we start up any LabKey instances on our hosted servers that had both the web server and database server shut off, we have to start up the database server first, give it a few minutes until the database server is fully up and no longer initializing, then start up the web server afterwards. This process can take about 15 minutes on average.