Error after installation

WordPress Information
WP Version: 5.4.2
WP Memory Limit: 256 MB
WP Debug Mode: No
WP Cron: Yes
Language: ru_RU
Server Information
Server Info: Apache/2.2.33-dev (Unix) mod_ssl/2.2.33-dev OpenSSL/1.0.1e-fips Phusion_Passenger/5.1.12 PHP/7.4.7 mod_wsgi/4.6.2 Python/3.6
CGI Version: CGI/1.1
PHP Version: 7.4.7
PHP Post Max Size: 256 MB
PHP Time Limit: 60
PHP Max Input Vars: 1000
cURL Version: 7.29.0, NSS/3.44
SUHOSIN Installed: –
MySQL Version: 5.7.30
Max Upload Size: 256 MB
Default Timezone is UTC: Yes
PHP Error Log File Location:
PHP Extensions: Core, date, libxml, openssl, pcre, sqlite3, zlib, bcmath, bz2, calendar, ctype, curl, dom, hash, fileinfo, filter, ftp, gd, gettext, gmp, SPL, iconv, session, intl, json, ldap, mbstring, standard, mysqlnd, mysqli, PDO, pdo_mysql, pdo_sqlite, Phar, posix, Reflection, imap, shmop, SimpleXML, soap, sockets, exif, sysvsem, sysvshm, tidy, tokenizer, xml, xmlreader, xmlrpc, xmlwriter, xsl, zip, apache2handler, imagick, memcached, redis, mongodb, Zend OPcache
fsockopen/cURL: Yes
SoapClient: Yes
DOMDocument: Yes
GZip: Yes
Multibyte String: Yes
Remote Get Status: Yes

I have the latest version – 7.4.7, what’s wrong?

After activating the plugin, a white bar appears on top of the entire menu. On the help page, the department selection button does not respond to pressing.