Error al ejecutar composer install

Florencia,

Muchas gracias, ahí instale la versión 1.10.17, y al ejecutar composer install me sale el siguiente error:

our requirements could not be resolved to an installable set of packages.

  Problem 1
    - The requested PHP extension ext-apcu * is missing from your system. Install or enable PHP's apcu extension.

Ejecute el siguiente comando apt-get install php-apcu y me devuelve que ya lo tengo instalado

Reading package lists... Done
Building dependency tree       
Reading state information... Done
php-apcu is already the newest version (5.1.19+4.0.11-7+ubuntu20.04.1+deb.sury.org+1).
0 upgraded, 0 newly installed, 0 to remove and 14 not upgraded.

que me estaría faltando?