Discord.js bot assigning roles to users throws permission denied error

I'm trying to make a discord bot (with js) that can assign roles to users. Discord version: 14.3.0 Nodejs version: 16.17.0

Im using this function to assign role.

const client = new Discord.Client({
    intents: [
    GatewayIntentBits.Guilds,
    GatewayIntentBits.GuildMessages,
    GatewayIntentBits.MessageContent,
    GatewayIntentBits.GuildMembers,
    GatewayIntentBits.DirectMessages
  ]
});
....

var role = message.guild.roles.cache.find(role => role.name == "Role_name")
guildMember.roles.add(role) // this line is causing the error

This is the exact error im getting

/node_modules/@discordjs/rest/dist/lib/handlers/SequentialHandler.cjs:293
    throw new DiscordAPIError.DiscordAPIError(data, "code" in data ? data.code : 
data.error, status, method, url, requestData);
          ^

DiscordAPIError[50013]: Missing Permissions
    at SequentialHandler.runRequest (    /media/pranav/Storage/ie/programming/nodejs/project-l    isabey/node_modules/@discordjs/rest/dist/lib/handlers/SequentialHandler.cjs:293:15)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async SequentialHandler.queueRequest (    /media/pranav/Storage/ie/programming/nodejs/project-l    isabey/node_modules/@discordjs/rest/dist/lib/handlers/SequentialHandler.cjs:99:14)
    at async REST.request (/media/pranav/Storage/ie/programming/nodejs/project-l    isabey/node_modules/@discordjs/rest/dist/lib/REST.cjs:52:22)
    at async GuildMemberRoleManager.add (    /media/pranav/Storage/ie/programming/nodejs/project-l    isabey/node_modules/discord.js/src/managers/GuildMemberRoleManager.js:129:7) {
  rawError: { message: 'Missing Permissions', code: 50013 },
  code: 50013,
  status: 403,
  method: 'PUT',
  url: '    https://discord.com/api/v10/guilds/1011546412011507823/members/1021733308457041970/roles/1    021714244846223360',
  requestBody: { files: undefined, json: undefined }
}

1. I tried giving the bot Mod permissions in the server
2. Invited bot to server with "discord.com/api/oauth2/authorize?client_id=xxxxxxxxxx&permissions=8&scope=bot%20applications.commands"
3. In developer portal all 3 "privileged gateway intents" are checked.

Still i'm getting the same error. How can I fix this ?

Thanks!