fluidsynth on Linux Mint complains

out.txt

▸ fluidsynth 
FluidSynth runtime version 2.1.1
Copyright (C) 2000-2020 Peter Hanappe and others.
Distributed under the LGPL license.
SoundFont(R) is a registered trademark of E-mu Systems, Inc.

Cannot connect to server socket err = Connection refused
Cannot connect to server request channel
fluidsynth: warning: Failed to set thread to high priority
jackdmp 1.9.12
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2016 Grame.
Copyright 2016-2017 Filipe Coelho.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
Cannot create RT messagebuffer thread: Operation not permitted (1)
Retrying messagebuffer thread without RT scheduling
Messagebuffer not realtime; consider enabling RT scheduling for user
no message buffer overruns
Cannot create RT messagebuffer thread: Operation not permitted (1)
Retrying messagebuffer thread without RT scheduling
Messagebuffer not realtime; consider enabling RT scheduling for user
no message buffer overruns
Cannot create RT messagebuffer thread: Operation not permitted (1)
Retrying messagebuffer thread without RT scheduling
Messagebuffer not realtime; consider enabling RT scheduling for user
no message buffer overruns
JACK server starting in realtime mode with priority 10
self-connect-mode is "Don't restrict self connect requests"
Cannot lock down 82280346 byte memory area (Cannot allocate memory)
control open "hw:Device" (No such device)
audio_reservation_init
Acquire audio card Audio0
creating alsa driver ... hw:0|hw:Device|1024|2|44100|0|0|nomon|swmeter|-|32bit
ALSA lib pcm_hw.c:1829:(_snd_pcm_hw_open) Invalid value for card
ALSA: Cannot open PCM device alsa_pcm for capture. Falling back to playback-only mode
configuring for 44100Hz, period = 1024 frames (23.2 ms), buffer = 2 periods
ALSA: final selected sample format for playback: 32bit integer little-endian
ALSA: use 2 periods for playback
Cannot use real-time scheduling (RR/10)(1: Operation not permitted)
AcquireSelfRealTime error
Cannot lock down 82280346 byte memory area (Cannot allocate memory)
Cannot use real-time scheduling (RR/5)(1: Operation not permitted)
JackClient::AcquireSelfRealTime error
Type 'help' for help topics.

> fluidsynth: panic: An error occurred while reading from stdin.
JackTemporaryException : now quits...
Jack main caught signal 2
control open "hw:Device" (No such device)
Released audio card Audio0
audio_reservation_finish