Initial setups often include extensive default configurations that can conflict with lab topologies. You can enter the configuration mode and use delete from the top hierarchy, but you must ensure the em1 interface configuration is preserved to keep the RE and PFE linked.
The PFE often defaults to VNC; it is generally better to switch this to Telnet for easier management in standard lab tools. download for vQFX 20.2 is actually 19.4 | Data Center vqfx202r110reqemuqcow2 top