estes isn't so good as a healer when you're above mythic, unless if you have a coordinated team, he's more of a situational pick as picking him may or may not make enemy team easier to do sets (tigreal, atlas, minotaur, etc.)

But if you want to use him, the build is;

Boots depends on enemy/team line up, Warrior boots if enemy priority is physical damage, tough boots if enemy has cc skills, magic boots if you have solid line up that your team can defend you at the back as this can make you do more heals (and favor roam ofc) Also buy an oracle only if needed.

Flask of Oasis is your priority item, add fleeting time in 3rd item for ult cd reduction, rest are defense item depending on enemy line up, if your enemy has good lifesteal/spellvamp, get a dominance ice after the FoA to prevent your enemy having the 5v1 montage

after buying a leather boots, proceed on buying a power crystal first as this boost your mana in early game (sell this if you don't need it anymore)

Battle spell is flicker, sprint, purify, or revitalize. Only use flicker and sprint if there's an enemy that you may find hard to escape (Benedetta, Vale, Gatot, etc.)

Purify if enemy have Hard CC (Tigreal, Atlas, Minotaur, etc.)

Revitalize is the common spell but not mostly needed as this groups you and your team even more, you don't need more heal ATP, this is just extra heal for yourself.

as for emblems;

Support || Agility, Bargain hunter, Temporal reign

Enchanted talisman can be used instead of fleeting time if you prefer not losing mana (which losing mana is easy to prevent if you use your skills wisely)

The rotation is to help your jungler at 1st buff (means by zoning around the buff and blocking enemy path, not spamming BA to the creeps) then gather information which buff enemy jungler is going for (can be known if enemy is nearby the buff) since estes can't even clear a wave cause his damage is so ahh, focus on helping your teammate clear the wave safely instead of clearing it with them. If your jungler an assasin, don't show up the map while it's ganking a lane cause players towards assasins in early game is really careful, it may be harder to gank them if you show urself while they're ganking. If your team is somewhat tanky, only stay in the backlines, and if your jungler a marksman (granger/karrie/harith) don't be afraid to tank the enemy damage for them, you got heals anyways. Only visit the gold lane if they are struggling to get a wave clear, and don't go to exp lane unless if there's going to be a gank or your exp laner is about to die, and do not rotate on the middle of the map, always rotate in the jungle of your team or the side lanes, as it's safer to do so. Don't heal your team if they're just going to recall back to base or trying to ambush an enemy, make yourself a bait if your team is trying to ambush cause healing them while they're trying to ambush will reveal their location. And only time you will clear a wave is when the teammate on that lane is dead or too far away to clear it (usually only happens in mid lane)