I installed chat app but I can't find the icon in the navbar?

I installed chat app
but I can’t find the icon in the navbar ?
How can I solve this problem ?

Frappe Chat has been discontinued, but you can still use it. However, it might not be fully compatible with version 15 due to several bugs.

also have problem when I install lms

bench install-app lms

An error occurred while installing lms: App lms not in apps.txt
Traceback with variables (most recent call last):
File “apps/frappe/frappe/commands/site.py”, line 481, in install_app
_install_app(app, verbose=context.verbose, force=force)
context = {‘sites’: [‘default’], ‘force’: False, ‘verbose’: False, ‘profile’: False}
apps = (‘lms’,)
force = False
_install_app = <function install_app at 0x7f06f0a06950>
filelock = <function filelock at 0x7f06f0a041f0>
exit_code = 0
site = ‘default’
app = ‘lms’
err = Exception(‘App lms not in apps.txt’)
File “apps/frappe/frappe/installer.py”, line 294, in install_app
raise Exception(f"App {name} not in apps.txt")
name = ‘lms’
verbose = False
set_as_patched = True
force = False
sync_jobs = <function sync_jobs at 0x7f06f087c940>
sync_for = <function sync_for at 0x7f06f087d360>
sync_customizations = <function sync_customizations at 0x7f06f213ab00>
sync_fixtures = <function sync_fixtures at 0x7f06f087d5a0>
app_hooks = {‘add_to_apps_screen’: [{‘name’: ‘lms’, ‘logo’: ‘/assets/lms/images/lms-logo.png’, ‘title’: ‘Learning’, ‘route’: ‘/lms’, ‘has_permission’: ‘lms.lms.api.check_app_permission’}], ‘after_install’: [‘lms.install.after_install’], ‘after_sync’: [‘lms.install.after_sync’], ‘app_color’: [‘grey’], ‘app_description’: [‘Frappe LMS App’], ‘app_email’: [‘jannat@frappe.io’], ‘app_icon_route’: [‘/lms’], ‘app_icon_title’: [‘Learning’], ‘app_icon_url’: [‘/assets/lms/images/lms-logo.png’], ‘app_license’: [‘AGPL’], ‘app_name’: [‘frappe_lms’], ‘app_publisher’: [‘Frappe’], ‘app_title’: [‘Frappe LMS’], ‘app_version’: [‘2.9.0’], ‘before_uninstall’: [‘lms.install.before_uninstall’], ‘doc_events’: {‘*’: {‘on_change’: [‘lms.lms.doctype.lms_badge.lms_badge.process_badges’]}, ‘Discussion Reply’: {‘after_insert’: [‘lms.lms.utils.handle_notifications’]}, ‘Notification Log’: {‘on_change’: [‘lms.lms.utils.publish_notifications’]}}, ‘fixtures’: [‘Custom Field’, ‘Function’, ‘Industry’, ‘LMS Category’], 'has_website_per…
installed_apps = [‘frappe’, ‘erpnext’, ‘hrms’, ‘payments’]
builtins.Exception: App lms not in apps.txt